1. Field of the Invention
The present invention relates to a novel plant growth regulator. More particularly, it relates to a plant growth regulator comprising, as its active component, one or more compounds selected from the group consisting of [+]-hexylitaconic acid, the dihydro derivative and lower alkyl monoesters thereof.
2. Brief Description of the Prior Art
Conventionally, there have been few physiologically active substances for plants that are naturally produced and actually being used at present. Among the few exceptions are gibberellic acids produced from Gibberella fujikuroi germs; cytokinin extracted from yeasts, coconut milk, fish sperms, etc.; plant auxines; ethylene gas; and the like. In particular, almost no physiologically active substances for plants produced from fungal metabolites have been known, and in the existing circumstances no physiologically active substances having effectiveness for plants corresponding to the usefulness of gibberellic acids have yet been discovered.
Especially in the field of acceleration of rooting, which is the main characteristic of the present invention, no substance produced from fungi has been discovered at all. As for the synthetic compounds, though some substances have been known such as IBA (2-indolebutyric acid), 2,4,5-T (2,4,5-trichlorophenoxy acetic acid), NAD (naphthalene acetamide), 2,4-D (2,4-dichlorophenoxy acetic acid), NAA (naphthalene acetic acid), abscisic acid and the like, the fact is that these compounds, when used for acceleration of rooting, have the deficiencies as set out below, and satisfactory uses thereof are quite limited.
(1) The use of these compounds is limited to acceleration of rooting by means of soaking the rooting parts in the chemicals. This is because these compounds lack movement within the plant, particularly basipetal movement within the plant. This can be said for all the aforementioned substances, IBA, 2,4,5,-T, NAD, 2,4-D, NAA and abscisic acid. PA1 (2) Since the effective concentration and the critical concentration causing chemical damage are very close, some compounds cannot be used safely. The above 2,4,5-T, 2,4-D, NAD, NAA and abscisic acid are examples. PA1 (3) Some of the compounds are problematic as regards their mamalian toxicity. The above 2,4,5-T and 2,4-D are the examples of such cases. PA1 (1) Their movement within the plant is great. Particularly, through foliar treatment they translocate into the lower parts of the plant and move therein to accelerate rooting. Thus they are quite convenient in use and very suitable for such purposes as growth promotion by acceleration of rooting and recovery of growth checked by environmental snags. PA1 (2) By treating cuttings of the plant with the substances, acceleration of rooting can also be effected. PA1 (3) Since safety to plants is quite high, they can be used safely from the early stage through the respective stages of growth. PA1 (4) Safety for mammalia is very high. PA1 214.1225 (M.sup.+, 5%, Calculated value as C.sub.11 H.sub.18 O.sub.4, 214.1195), PA1 196.1074 (M-H.sub.2 O, 5%; Calculated value as C.sub.11 H.sub.16 O.sub.3, 196.1034), PA1 178.1010 (M-2H.sub.2 O, 5%; Calculated value as C.sub.11 H.sub.14 O.sub.2, 178.0994), PA1 169.1246 (M-COOH, 43%; Calculated value as C.sub.10 H.sub.17 O.sub.2, 169.1229), PA1 129.0117 (M-C.sub.6 H.sub.13, 55%; Calculated value as C.sub.5 H.sub.5 O.sub.4, 129.0188), PA1 112 (M-C.sub.6 H.sub.12 -H.sub.2 O, 100%);
While the conventional chemicals have the unsolved problems as pointed out above, the naturally produced substances of the present invention have the following advantages:
Since the substances of the present invention make it possible to overcome the problems of the conventional chemicals, their agricultural and horticultural usefulness is remarkable.